The invention relates to a safety switch for a guard device associated with a machine or device.
Guard devices of this type prevent persons from being able to get within the danger range of a machine or device as long as the machine or device is in operation. To that end, the door or the like that allows access is monitored by a safety switch, which allows the machine or device to be turned on only if the door or the like is closed, and which stops the machine or device if the door or the like is opened.
The known safety switches of the type referred to at the outset are actuated by means of a key, which can be introduced into a channel provided in the head of the switch and removed from it again. Both when the key is inserted into the switch head and when it is removed, a switchover of the switch takes place, in the one case preferably by compulsion, because of the force exerted on the key.
The known safety switches have the serious disadvantage that whenever the switch head comes loose from the switch housing, especially in response to externally exerted force, breakage occurs that causes disconnection; the tappet of the safety switch, because of the restoring force exerted on it, changes over to the switching state in which the machine or device can either be turned on or stays on. If the disconnection of the switch head from the switch housing occurs when the door or the like of the guard device is open or is being opened, then the protection sought by means of the guard device and the safety switch is entirely lacking.